[Ffmpeg-devel] [RFC] rtjpeg decoding functions

[Michael Niedermayer]

Hi

On Tue, Jan 17, 2006 at 09:03:11PM +0100, Reimar D?ffinger wrote:
> Hi,
> the attached patch constains (untested) rtjpeg decoding functions. These
> are _not_ in a decoder module, since I do not know of any pure rtjpeg
> codec, and nuv must select between different codings on a per-frame
> basis.
> Any comments or a "testbed" are welcome.
[...]
> +    uint8_t dc = get_bits(gb, 8);
> +
> +    // block not coded
> +    if (dc == 255)
> +       return 0;
> +
> +    // number of non-zero coefficients
> +    coeff = get_bits(gb, 6);
> +    memset(&block[coeff + 1], 0, 63 - coeff);
> +
> +    // 2 bits per coefficient
> +    while (coeff) {
> +        ac = get_sbits(gb, 2);
> +        if (ac == -2)
> +            break; // continue with more bits
> +        PUT_COEFF(ac);
> +    }
> +
> +    // 4 bits per coefficient
> +    align_get_bits_to(gb, 4);
> +    while (coeff) {
> +        ac = get_sbits(gb, 4);
> +        if (ac == -8)
> +            break; // continue with more bits
> +        PUT_COEFF(ac);
> +    }
> +
> +    // 8 bits per coefficient
> +    align_get_bits_to(gb, 8);

if all the 8bit codewords are 8bit aligned then the bitstream reader seems
a less then ideal way to read them, same for 4 and 2bit aligned stuff

[...]

-- 
Michael